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Join science editor @MoNscience today for another Q&A on #COVID19 at 1pm ET. Reply below with questions and read more here
https://on.natgeo.com/34EToQ4
https://on.natgeo.com/34EToQ4
Letâs clear up some terms here.
COVID PCR tests are highly accurate. Theyâre both sensitive (i.e., can detect low amounts of viral RNA from a swab) and specific (i.e., can distinguish SARS-CoV-2 from other viruses) https://twitter.com/comtnsbrews/status/1322200657231638529?s=20
COVID PCR tests are highly accurate. Theyâre both sensitive (i.e., can detect low amounts of viral RNA from a swab) and specific (i.e., can distinguish SARS-CoV-2 from other viruses) https://twitter.com/comtnsbrews/status/1322200657231638529?s=20
The bigger issue with testing in the U.S. is timing...
Early on after exposure/infection, the virus takes time to multiply. So during the first 4-7 days, the viral loads in the body may be too low for detection by PCR, even though a person may be contagious during this time. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30773-8/fulltext#supplementaryMaterial
But notice, after a virus takes hold, the body can take several weeks to clear it, even though the person may no longer be contagious, hence why people can still test positive on PCR.
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30773-8/fulltext#supplementaryMaterial
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30773-8/fulltext#supplementaryMaterial
In other words, COVID PCR testing itself is not flawed. The issues are when and how we use it.
Thatâs why guidelines on contagiousness revolve around both the timing of testing and when symptoms resolve.
Thatâs why guidelines on contagiousness revolve around both the timing of testing and when symptoms resolve.
WHO: https://www.who.int/publications/i/item/criteria-for-releasing-covid-19-patients-from-isolation
CDC: https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html
CDC: https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html
Notice in those CDC guidelines, the centers do NOT call for retesting within the first three months after an initial positive result. https://twitter.com/comtnsbrews/status/1322201110363267074?s=20
The CDC has just released its protocols for investigating reinfection ( https://www.cdc.gov/coronavirus/2019-ncov/php/reinfection.html) But the rules for isolation after reinfection remain the same: It can end 10 days after symptom onset and resolution of fever for at least 24 hours
This question might be on your mind because of an Oct. 26 study about COVID-19 antibodies that went viral. https://twitter.com/garciaa_brody/status/1322194420674932737?s=20
Hereâs the thing: No one knows yet how long COVID-19 immunity lasts in terms of immune protection and this new study does NOT answer that question. https://twitter.com/TwitterMoments/status/1321115274263826432
âŠas followers of my twitter already know. 
https://twitter.com/MoNscience/status/1321088509894156289
https://twitter.com/MoNscience/status/1321088509894156289
Waning antibody levels are a normal part of an immune response. Also, the phenomenon doesnât mean that a personâs antibody shield has gone away.
Think of it this way: Once you finish putting out a fire, you donât leave the hose running. But you also donât throw away the hose.
Think of it this way: Once you finish putting out a fire, you donât leave the hose running. But you also donât throw away the hose.
For more, check out this story by @edbites. It explains why there is more to a personâs COVID-19 immunity than antibodies. https://on.natgeo.com/3jGwA6T
I love a good opportunity to chat about best practices with COVID-19 news consumption. https://twitter.com/curtisc5105/status/1322197190513741826?s=20
Youâre referring to this Sept. 24 story in The Guardian? https://www.theguardian.com/world/2020/sep/24/close-to-100-accuracy-airport-enlists-sniffer-dogs-to-test-for-covid-19
Did you notice that the research is âpreliminaryâ and that the team didnât provide actual data nor a report?
Did you notice that the research is âpreliminaryâ and that the team didnât provide actual data nor a report?
In fact, researchers in the United States are looking at the potential for using dogs to screen for COVID-19.
Audrey R. Odom John from @ChildrensPhila presented results on a preliminary study last week during @IDWeek2020 https://fb.watch/1s3XxsPG24/
Audrey R. Odom John from @ChildrensPhila presented results on a preliminary study last week during @IDWeek2020 https://fb.watch/1s3XxsPG24/
Notice the sensitivity/specificity for canine sniffers
For normal PCR testing, those values tend to be 97% and 100%, respectively.
In other words, PCR testing is way more accurate at spotting SARS-CoV-2 and less likely to confuse it for another virus. https://www.idsociety.org/globalassets/idsa/practice-guidelines/covid-19/diagnostics/idsa-covid-19-guideline_dx_version-1.0.1.pdf
For normal PCR testing, those values tend to be 97% and 100%, respectively.
In other words, PCR testing is way more accurate at spotting SARS-CoV-2 and less likely to confuse it for another virus. https://www.idsociety.org/globalassets/idsa/practice-guidelines/covid-19/diagnostics/idsa-covid-19-guideline_dx_version-1.0.1.pdf
Also, if you watch Dr. Odom Johnâs presentation, youâll learn that the sniffer tests required urine samples from people.
As @jane_c_hu wrote in August, these logistical constraints limit the utility of COVID-sniffing dogs. https://slate.com/technology/2020/08/covid-19-sniffing-dogs.html
As @jane_c_hu wrote in August, these logistical constraints limit the utility of COVID-sniffing dogs. https://slate.com/technology/2020/08/covid-19-sniffing-dogs.html
Tl;dr: Itâs fascinating that humans give off scents related to being infected with the coronavirus, but donât hold your breath on COVID-sniffing dogs.
General rules of thumb:
1. Symptoms tend to start 4 to 6 days after exposure/infection with the virus, but it can take up to 14 days.
2. The infectious period starts 1 to 3 days before symptoms begin.
https://theconversation.com/how-long-are-you-infectious-when-you-have-coronavirus-135295
https://twitter.com/Soulsol7/status/1322233371980943361
1. Symptoms tend to start 4 to 6 days after exposure/infection with the virus, but it can take up to 14 days.
2. The infectious period starts 1 to 3 days before symptoms begin.
https://theconversation.com/how-long-are-you-infectious-when-you-have-coronavirus-135295
https://twitter.com/Soulsol7/status/1322233371980943361
Takeaway: A person can be contagious before symptoms arise. Indeed, this scenario explains 50% of new cases in the United States.
So if you know that youâve been exposed to a #COVID19 case or youâre showing symptoms, kindly stay home. https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/quarantine.html
So if you know that youâve been exposed to a #COVID19 case or youâre showing symptoms, kindly stay home. https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/quarantine.html
Hard to say now how common reinfection will be, given only a handful of cases have been confirmed so far.
Earlier this month, @VirusesImmunity wrote a nice breakdown for @TheLancetInfDis
https://doi.org/10.1016/S1473-3099(20)30783-0 https://twitter.com/AnupamkPandey/status/1322231180339503104?s=20
Earlier this month, @VirusesImmunity wrote a nice breakdown for @TheLancetInfDis
https://doi.org/10.1016/S1473-3099(20)30783-0 https://twitter.com/AnupamkPandey/status/1322231180339503104?s=20
Based on past experience with highly contagious coronaviruses (namely the ones that cause colds), I would expect reinfections to eventually happen on a broad scale.
Regardless, the equation for overcoming COVID-19 remains the same: social distancing, good hygiene, wear masks, test as fast as you can, isolate the sick.
For more, see this story from August by @CraigAWelch https://on.natgeo.com/3ebKMUd
For more, see this story from August by @CraigAWelch https://on.natgeo.com/3ebKMUd
And as I wrote earlier this month, this advice applies until we have a highly effective vaccine. https://on.natgeo.com/3kLvl7L
Thatâs an interesting one.
So, the entire planet isolatesâŠno one broke the rulesâŠand we somehow kept cases from spilling from hospitals.
Yes. If you think about it, thatâs essentially what New Zealand, Thailand, and Taiwan have done. https://twitter.com/Tom18369195/status/1322242794493194244?s=20
So, the entire planet isolatesâŠno one broke the rulesâŠand we somehow kept cases from spilling from hospitals.
Yes. If you think about it, thatâs essentially what New Zealand, Thailand, and Taiwan have done. https://twitter.com/Tom18369195/status/1322242794493194244?s=20
(South Korea too, for the most part.)
As much as people fight over masks and lockdowns, the solution has been the same since the beginning:
If everyone follows the health guidance, COVID-19 cases will drop and we can safely reopen, even before a vaccine is ready.
If everyone follows the health guidance, COVID-19 cases will drop and we can safely reopen, even before a vaccine is ready.
If we donât come together to beat this pandemic, people will continue to suffer.
For example, a silent physical and mental health crisis is emerging among thousands of kidney disease patients, as @edbites reports for us. https://on.natgeo.com/2TFku3i
For example, a silent physical and mental health crisis is emerging among thousands of kidney disease patients, as @edbites reports for us. https://on.natgeo.com/2TFku3i
